Rotary underreamer



June 16, I931.

s. L. CAMPBELL 1,809,820

ROTARY UNDERREAMER File d Dec. :5, 1927 3 Sheets-Sheet 1 June 16, 1931. s. CAMPBELL 2 ROTARY UNDERREAMER Filed Dec. 3, 1927 3 Sheets-Sheet 2 961002424. fawpezl.

June 16, 1931. s. L. CAMPBELL 1,809,820

ROTARY UNDERREAMER Filed Dec. 3; 1927 3 Sheets-Sheet 5 1 casing Patented June 16, 1931 UNITED VS-TALTES i PATENT; OFFICE STEWART L. CAMPBELL, on BERKELEY, CALIFORNIA, ASSIGNOR T Los 'ANGELES, CALIFORNIA ROTARY UNDER-REAMER Application filed December 3, 1927; Serial No. 237,358.,

' This invention. relates to rotary underreamers or expansive reamers designedi'particularly for rotary drilling, and the present invention is somewhatofthe same nature as that set forth in my prior application Serial No. 85,126, filedlFebruary 1. 1926,. now Patent N 01,667,190, dated April 24; 1928,

entitled Rotary underreamer, both these inventions involving reamers which utilizeja cutter or 1 cutters swinging about eccentric; vertical axes. The present invention involves certain improvements having more particularly to do with the mounting ofthe cutters, 5

the means whereby swinging movement its obtained, and the manner of assemblingand disassembling the reamer.

In the following. specification I explain in the specificldetail preferred and illustrative embodiments of the present invention, re'ference for this purpose being had to the'accoin ganyingdrawings, in which I Fig. 1 is a side elevation ofan'underreamer inaccordance with the present invention; f Fig. 2 is a. central longitudinal sectionof the same, with parts shown in elevation for clarity of illustration;

fFigs. 3 and 4 are cross-sections on the rep 'sembly and disassembly thatthebody is made spective lines 3 3 and/k ofFig.'-2,but showing the cutters expanded, whereas Figs. 1 and 2 show them contracted;

Fig. 5 is a section'online 5 5QofQFig. 1, showing the cutters contracted inside-awell casing;

"Fig. 6 is a section on. line 6 6 of Fig.1, showing the cutters contracted insidejawell Fig. 7 is asimilarsectionshowingthe cutters expanded; i i f Fig. 8 is an elevation,;withpartsjbroken away in section, of the interiorrparts of the reamer; showing the reamer in partial state of disassembly; I

- Fig. 9 is an end view of the parts shown in Fig. 8; I e l r f Fig. 10 is across section on line 10'10'of Fig. 2;

Figs. 11 and 12 are detail views showing varying forms of cutters which may be used in the reamer;

Fig. .13 is a i m r e ertieeeei Fig. 2, showing a modified construction;

on line 14-14 of body madeup of an interiorbody core .10

and an exterior tubular shell 11 which fits over theinteriorbody core and is secured thereto at-its upperend. The shell maybe rotatively secured to the core by means of spaced lugs .13 which enter corresponding recesses 14 inthe body core; and such means as bolts or cap screws 13 may be used to.

preventrelative longitudinal movement be tweenthe core'and the shell. "In some of the JOHN" GRANT, OF

broader aspect-sot the invention'the core and shell may'be regardedas forming a single p ece body; and this is; true so far as all functional operations of. the reamer are concerned; is as regards convenience of asof two parts.

,The body core "has below the lower end 311611.11, when they are in collapsed position, and swinging outwardly to project their outer ends or edges. beyond the periphery of shellll whenfexpanded. [Below the reduced portion 15. the ,b0dy' has an enlargement 56 is also; formed as hereinafter'described, to

allow of ready removal of the cutters from the body. Below the. enlargement. 56' the body has the usual screw-threaded pin 17 for connection with a drill bit 18, the "water courses 19 of the drill bit being fed through eer a s renewals e ia v h fa-longitudinal water course 20 which extends a i through the whole length of the body. The

which is lforrnjed toaflord a' bearing block? I for the-lower ends ofthe cutter stems, and

usual screw-thread pin 21, for connection with a rotary drill stem.

Any suitable number of cutters may be used. In the particular illustration here I prefer to show four, these cutters being preferably equally spaced around the central axis of the tool; Thebody core thus is provided with four equally spaced longitudinal bores 23 which take, and preferably form bearings for, the cutter stems 24. In the specific form here shown I prefer to show the cutters mounted on their stems so that the stems and cutters rotate together. This provides a convenient arrangement whereby torsion springs may be applied directly to the stems for the purpose of swinging the cutters. Thus, the cutter stems 2 1 extend up through the bores 23 into and preferably completely across recesses 25, these recesses being sunk in from the exterior surface of the body core and being normally covered by the shell 11.

A coiled torsion spring 26 is applied to each cutter stem within a recess 25, the torsion spring surrounding the cutter stem, having one end anchored at 26a to the cutter stem and the other end connected at 26?) to the body, Any suitable arrangements for anchoring the ends of the spring may be utilized; as shown in Fig. 2, one end of the spring may simply be set in a hole or recess in the body and, as shown in Fig. 10, the other end of the spring may simply be entered into a hole in the stem. hen the parts are assembled these springs are tensed so that they will tend at all times, with proper force, to swing the cutters to their expanded positions-the positions shown in Figs. 3, 4 and 7; and the cutters must be moved to the contracted positions of Figs. 5 and 6 against the tensions of the springs.

The cutter 16 may be of any desired charactor, and may have a formation-cutting edge of any desired type. In most of the figures of the drawings I show cutters 1.6 in the simple form of blades having a'formation shearing edge 16a, or an inset blade 16) (see Fig. 1) which presents a downwardly facing cutting edge at the'lower horizontal edge ofmember 16; but, as shown in Figs. 11 and 12, the cutter members 16 may carry other types of cutting elements, such as a rotatable toothed roller 166. In Fig. 11 the blade 16 is shown recessed at 160 to take rollers 167), while in Fig. 12 the blade is shown as if it were entirely cut through, leaving only what may be regarded as the crank arms 16d, which carry the roller supporting pin or trunnion 16?).

Here the parts 16d and 166 form the rigid part of the swinging cutter, and may be rearded as a swinging cutter carrier to carry roller 16b. Likewise, in Fig. 11, blade 16 may be regarded as a cutter carrier, which carries ultimate cutting element 16?): and similarly in theother figures the blades 16 may be regarded. as cutter carriers or cutter elements which carry the ultimate cutting elements, being in that case the cutting or shearing edge 16a or blade 16f.

Regardless of how the ultimate cutting element may be formed or provided, cutter elements 16 are, as before described, mounted to be swung on their stems 24 between the expanded and collapsed positions shown in the several views. In their expanded positions the outer cutting elements of members 16 project beyond the periphery of shell 11, and the cutters 16 back up against stop shoulders 30 which are formed on the body, and, in this specific design here illustrated, are formed on the lower edge of body shell 11. The cutter stems 24 rotate on axes eccentric of the central axis of the whole tool; and it will be noted that the stop shoulders 30 are located so as to limit swinging movement of the cutters to such positions that they are, in their expandedpositions, non-radial to the central axis of the tool. In its expanded position, no part of the cutters can reach a position where the line drawn through the central axis of the body, and through the swinging axis ofthe cutter, will pass through any part of the cutter which lies outside the body of the tool, and which is therefore engaged, or liable to be engaged, by the lower end of the casing when the cutters are collapsed.

The upper outer corner of each cutter 16 is beveled off, as shown at 40, over its entire edge surface. In the drawing this beveling is shown as curvedin elevation outline, but that is immaterial, as thebeveling may be of any desired configuration in elevation.

,lVhatever such'elevation configuration may be, the beveled face is preferably made of such form as to present a surface for engaging with the bottom of the casing or the casing shoe, rather than a mere line. This characteristic of the beveling is illustrated in Figs. 6 and 7.

Fig. 6 is a horizontal section showing the cutters collapsed inside the casing, the section "of the bevel 40; and, as shown in Fig. 7, this contour line near the upper ends of the cutters, is, when the cutters are expanded, substantially concentric with the central axis of the tool and therefore also with the casing. Consequently, the lower edge of the casing will engage the cutters, not on a sharp edge,

but along a somewhat extended contour line;

and this line of engagement may preferably, as shown in the drawings, extend clear across the Whole beveled edge of the cutter, As the tool is moved up -through, the casing, the cutters are swung in toward thefposition of Fig. 6. The contour line 40a is thus of course thrown out of concentricity 'withthe tool center, but the lowerv parts of'beveled js'urface 40 are shaped so that, as the casing edge moves relatively downwardly on the cutters and the cutters are swung in, the cutters still present a contour, line of engagement to the casing edge. Thus, when the cutters are in fully collapsed position, with their outer edge faces, resting against the interior of the easing, their contour lines illustrated at 4061 (the lowermost contour lines of the beveled faces) are substantially concentric with the tool axis and with the casing. Where a shear ing edge cutter of the type shown in Fig. 6 1s used, it maybe advisable to make this lowermost contour line, and the outer v peripheral edge face of the cutter, not quite exactly concentric with the casing, in order to remove the vertical shearing edge 16a, just shghtly from'the interior casing face, or to take off the pressure of that edge on the casing just enough to keep that edge from cutting into the casing when the toolis being moved through thecasing. Thus the center of the lowermost contour line d, with the terially change the'fact that the edge faceof the cutter engages the'casing inte'riorpreferably on a rather broad face ofengagement,

rather than'on a single verticalline of engagement. And,-'in anycase, itwill be seen that the cutter never engages the casing at a sharp edge only, always engaging the casing at least in a medial portion of thebeveled face 40, and preferably engaging the casing,

as far as is practical, across substantially the whole of that beveled face. What I have said of the contours illustrated: by the lines 40a and 40d isalso true of the intervening horizontal COIltOllISfttQb' and 40c of .the"

beveled face. 1

To explain more completely theconfiguration and action ofitheupper bevelledcut- 'ter faces, Figs. 15 J and 16 are referred to. Theplan'view of Fig. 16 exaggerates the cur- Vature of the arcuate contour lines 40ai40 d to clearly show thatthese arcs do notha'vethe same center but do have equal radii. These figures, show diagrammatically; the ;motion of one cutter withreference tothe casing' or "pipe, being inthefnature of'a horizontal secition through the cutter at the levellat'which,

expanded, it strikes the lower inner edge of the'pipe or shoe. -Thus the full line showing in Fig. 15 shows the cutter justas it is shown,

expanded, Fig. 7; and the contour line 40a is shown, as inFig. 7, as a contour-line in the cvlindric inner surface 7 a th p p indicated pythe circul r line'Q- a 5 Now, as thecutterswings in toward collapsed position it. successively takes the positionsf shown in dotted lines, Fig. 15, indicated 5Qa+5OcZ. It of eoursetalres an infinite number of such positions, but fourwill suifice for illustration and description. .The cutter reaches these intermediate positions by being pulled upinto the casing; so a horizontal section at the loweredge of the pipe (that is, what Fig. 15 is) will show successive contours 40a-40d on the bevelled cutter'corner atthe said levelhaying as centers a, b, c and d respectively. And each of these successive contours are, as the cutter swings inwardly'by reasonof pipe contact, also in thecylindric inner surface C of the pipe, and therefore,,in the then position of the cutter, concentric with the pipe center and the axis of the reamer. V p p g V Thus, for position 50a the contour 40a is shown to coincide withthe pipe surface;

and for position 50?) the contourOb. i For entirely collapsed position the contour. 40d has been explained. It will accordinglynow be understood that the bevel at thev cutter. corner-is of such shape or curvature that,

illustrated by contours,- it has, in any one of its successive swingingpositions, a contour in -the horizontal plane of the lower end of the pipe, which contour is located substantially in the inner cylindric surface of the pipe. In other words, thecutter has a bevelled sur- 1 face that can be described and, located by horizontal planeqcontours that, as the cutter swings inwardly, are successively concentric with-thepipe center and located ina circle or cylindercorrespondingin diameter with the inner surface of the pipe or shoe. These several contours are not all, at any one time or cutter =-p0s1t1on, so concentric; only one 1S-'S0COI1CIltI10 fOI- anyone cutter posltion.

That fact is'illustrated bythe concentric po- I "sitionw-oficontour 40a in the full line show: ing in Fig. 15, and'by the dotted line showings of 'contours'40b and 40d on the fulll-ine showing of. the cutter in Fig. 15. Only-con- :tour40a is concentric in that full line posi-' tion; vand'contours 40b, L00 and 40d don'ot become concentricuntil the cutter hasswung inwardly to the, corresponding positions. But, thesuccessive contours, of which only a, few areshown in Fig. 15,. becoming. thus successively, concentric 1 as the cutter swings ;in,'it willnow beseen how the cutter presents to the pipe, at all times'and in all position's, a line. ofcontact extending horizon- V Itally across its pipe contacting edge or sur-' face, rather than a mere point of contact; the pipe contactingflsurface of the cutter being made up of, or defined by, a series of ju'stsuch lines; y 7

Where rollers are used,-as-inFigs. 11 and '12, they preferably project somewhat beyond the outer 'edgeisurface of member 16; butthe upper ends. of'the rgllers are. tapered @S. at

"40f'to form substantial continuations of the "bevels 40 and so that the casing may continue to have the same collapsing action on the rollers as it has had on the bevel surface 40 as the tool is moved up into the casing.

From What has been said it will now be readily understood how the cutters are thrown from their expanded to their con tracted positions by engaging with the casing; the fact that the cutters are limited in all their projecting parts to non-radial positions, and the fact that the cutters engage the casing on abroad beveled face, insuring easy collapsing action without any liability of the cutters digging into the casing and binding. In their positions as collapsed by casing engagement, the cutters are somewhat in the position shown in Figs. 5 and 6; but they may move somewhat further inwardly until they are collapsed entirely within the circle of the body. In order to accommodate this further collapsing movement, and at the same time to allow the cutters at their pivoted edges to bear inwardly against the reduced portion 15, when expanded, the inner faces of the cutters may be somewhat recessed as is indicated at 50. This slight 'recessing allows the cutters to move to their collapsed positions and still have their rounded pivoted edges in engagement-with the reduced part and the reduced part, particularly when the cutters are expanded,acts as an abutment to take stresses directly from the cutters to the body without putting undue strains upon the cutter stems. F or instance, in'Fig. 4, the direction of rotation of the tool is left-handed (Fig. 4 being a bottom view). The cutting stress exerted on the outer cutting edge of the cutter 16 is therefore in the direction indicated by the arrow applied to the uppermost cutter, as shown a in Fig. 4. Such stress induces a stress of the cutteragainst the stop shoulder in the direction indicated by the arrow applied at that shoulder; with the result that a. pressure stress is developed at the pivotal edge of the cutter against the reduced part 15 in the direction indicated by the arrow applied at.

that point in Fig. 4. Consequently, the direct bearing of the pivoted edge of the cutter against the part 15 takes substantially all pressure and shearing stress off the cutter stem 24, relieving that stem of any liability to be bent or sheared. I

shown each cutter has a lower extension stem 24a which extends down below the cutter and into enlargement block 56. In one form of side wall makes with the plane determined by the center of theteol and the center of the corresponding cutter being less than the anis indicated most clearly in Fig. 7.

I In the'normal assembled position, the lower ends of stems 24a rest upon the upper'end surface of drill bit 18, and by removing the drill bit, andafter shell 11 and springs 26 have been removed, the cutters may be moved downwardly far enough to disengage them from shoulders 30, the normal clearance between the lower edges of cutters 16 and the upper face of block 56 being greater than the vertical dimension of shoulders 30. Consequently, a cutter 16 may bemoved down below shoulders 30 and then may be turned a little further outwardly to such' a position.

shown in Fig. 9, and then the cutter and its stem may be slipped directly downwardly andout through the notch 55. This operation is indicated in Figs. 8 and 9. The lower corner of the notch wall may be beveled off, as indicated at 550, to facilitate registration of cutter 16 with the notch when assembling the tool.

On the other hand, a'modifiedconstruction maybe utilized wherein the enlargement 560, may be made removable from the core 10, as is illustrated in Figs. 13 and 14. Block 56a is then removable downwardly from the body after the drill bit 18 has been removed; and

1 then the cutters are removable directly downwardly after shell 11 and spring 26 have been disengaged. In this case it is only necessary that the block 56a have vertical bores to take the stems 24a, as is indicated in Figs. 13 and 14, and it is unnecessary that there be clearance between the lower edges of the cutters and the upper face of the bearing block. T o prevent rotation of the bearing block on the body they may be splined together in any suitable manner, such as by the formation indicated at 60 in Fig. 14;.

I claim:

1. In an expansive tool of the character described, the combination of a body adapted to be passed through a well pipe, :1 horizontally swinging cutter element mounted on a vertical axis eccentric of the bodyaxis and adapt- 5 ed to swin outwardlv to a 0'. 'ti h 't In the particular form and design here F a p ql on W ere 1 S outer part is projected beyond the body and through which the tool has passed, means limiting movement of the cutter element to a position where its projectingpart is non-radial to the body axis, and the upper corner of the projected cutter part being beveled to a surface having, in a cylindric surface of a diameter substantially equal to the inner diameter of said Well pipe, horizontal contours which are successively, in downward progression. as

the cutter swings inwardly, substantially convertical axis eccentric of the body axis and adapted to swing outwardly-to a position where its outer part is projected beyond the,

body and beyond the interior diameter of the well pipe through which the tool has passed, means limiting movement of the cutter element to a position whereits projecting part is non-radial to the body axis, and the upper corner of the projecting cutter part being beveled to a surface that presents continuouslya.

horizontal line of contact to a casing edge as the cutter 1s moved up nto, and 1s swung 1nwardly by, such casing.

3. In an expansive tool of the character de scribed, the combination of a body adapted to be passed through a well pipe, a horizontally swinging cutter element mounted on a vertical axis eccentric of the body axis and adapted to swing outwardly to a position where its outer part is projected beyond the body and beyond theinterior diameter of the well pipe through which the tool has passed, means limiting movement of the cutter element to a position where its projecting part is non-radial to the body axis, and the upper corner of the projecting cutter part being beveled to a surface that presents continuously a surface portion between its edges to a casing edge as the cutter is moved up into, and is swung in wardly by, such casing, thereby to preventedges of the cutter from digginginto the casing.

where its outer part is projected beyond the- 4. In an expansive tool of the characterdescribed, the combination of a body adapted vertical axis eccentric of the body axis and adaptedto swing outwardly to a position where its'outer, part is projected beyondthe body and beyond the interior diameter of the well pipe through which the tool has passed, means limiting movement of the cutter element to a position where its projecting part.

is non radial to the body axis, the upper corner of the projecting cutter part being beveled to a surface that presents continuously a horizontal line of contact to a casing edge as the cutter is moved up into, and is swung inwardly by, such casing; and a roller cutter mounted: on the swinging cutter element and having an upper tapered part which forms a substantialcontinuation of the bevel on the cutter element.

6. In an expansive tool of the character described, the combination of a body adapted to be passed through a well pipe, a horizontally swinging cutterelement mounted on a verticalaxis eccentric of the body axis and adapted to swing outwardly to a position where its outer part is projected beyond the body and beyond the interior diameter of the well pipe through which the tool has passed, means limiting movement of the cutter element to a position where its projecting part is non-radial I to the body axis, the upper corner of the projecting cutter part being beveled to a surface that presents continuously a surface portion between its edges to acasing edge as the cutter is moved up into, and is swung inwardly by, such casi'ng,-thereby to prevent edges of the cutter from digging into the casing; and a roller cutter mounted on the swinging cutter element and having an upper tapered part which forms a substantial continuation of the bevel on the cutter element.

In witness that I claim the foregoing I hav;

hereunto subscribed my name this 26th day of Nov., 1927. v

' STEWART L. CAMPBELL;

s body and beyond the interior diameter of the well pipe through which the toolhas passed,

means limiting movement of the cutter element to a position where its projecting part is non-radial to the body axis, and the u per corner of the projecting cutter part being evsubstantially concentric with the body axis;

and a roller cuttermounted on the swinging cutter element and havlng an upper tapered part which forms a substantial continuation of the bevel on the cutter element.

5. In an expansivetool of the character described, the combination of a'body adapted to be passed through a well pipe, a horizontally swinging cutter element mounted on'a' 

